Securities (Narrative) (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Reclassification from held to maturity securities	$ (91,324,000)	$ (236,283,000)
Reclassification to debt securities available for sale	3,294,361,000
Equity securities with a readily determinable fair value	18,435,000	17,086,000
Equity securities with a readily determinable fair value	18,435,000	17,086,000
Unrealized gain on equity securities, net	525,000	212,000	$ 0
Gross realized gains (losses)	0	0	$ 0
FHLB stock	16,800,000	$ 16,600,000
Collateral Pledged
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Securities pledged as collateral	$ 509,600,000

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

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